Disturbance of midlatitude electrodynamic parameters due to the magnetospheric convection

Two case studies of ionospheric disturbances in electric fields, currents, and winds during periods of geomagnetic storms detected by incoherent scatter radar are presented. The disturbances are shown to originate from two distinct physical mechanisms: penetration of electric fields to lower latitudes during times of rapid change in magnetospheric convection; and the action of the disturbed ionospheric dynamo driven by storm induced wind disturbances. One storm illustrates penetrative convection electric fields when the Bz component of the interplanetary fields turns southward and northward. The observed events on the following day are clearly identifiable as the delayed response of the disturbance ionospheric dynamo.